1. Field of the Invention
The present invention relates to an object lens and a condenser that is mounted on a microscope and that can be used for dark field observation.
2. Description of the Related Art
Object lens and condensers mounted on microscopes and so forth have been used for not only regular bright field observation, but dark field observation. The dark field observation is performed by supplying a light beam from the periphery of an optical system such as an object lens or a condenser lens and guiding the light beam to the surface of an object. Thus, the dark field observation can be performed for samples that have flaws, foreign matter, unevenness, gap, or low reflectivity that cannot be observed by the bright field observation (for example, see FIG. 1 and so forth of Japanese Patent Application Laid-Open Publication NO. SHO 60-225817).